title: Histone deacetylase inhibition with valproic acid downregulates osteocalcin gene expression in human dental pulp stem cells and osteoblasts: evidence for HDAC2 involvement.
abstract: Adult mesenchymal stem cells, such as dental pulp stem cells, are of great interest for cell-based tissue engineering strategies because they can differentiate into a variety of tissue-specific cells, above all, into osteoblasts. In recent years, epigenetic studies on stem cells have indicated that specific histone alterations and modifying enzymes play essential roles in cell differentiation. However, although several studies have reported that valproic acid (VPA)-a selective inhibitor of histone deacetylases (HDAC)-enhances osteoblast differentiation, data on osteocalcin expression-a late-stage marker of differentiation-are limited. We therefore decided to study the effect of VPA on dental pulp stem cell differentiation. A low concentration of VPA did not reduce cell viability, proliferation, or cell cycle profile. However, it was sufficient to significantly enhance matrix mineralization by increasing osteopontin and bone sialoprotein expression. In contrast, osteocalcin levels were decreased, an effect induced at the transcriptional level, and were strongly correlated with inhibition of HDAC2. In fact, HDAC2 silencing with shRNA produced a similar effect to that of VPA treatment on the expression of osteoblast-related markers. We conclude that VPA does not induce terminal differentiation of osteoblasts, but stimulates the generation of less mature cells. Moreover, specific suppression of an individual HDAC by RNA interference could enhance only a single aspect of osteoblast differentiation, and thus produce selective effects.
authors.affiliation: Dipartimento di Medicina Sperimentale, Sezione di Istologia (TERM Lab.), via L. Armanni, 5, Secondo Ateneo di Napoli, Napoli, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Paino
authors.forename: Marcella
authors.initials: M
authors.lastname: La Noce
authors.forename: Virginia
authors.initials: V
authors.lastname: Tirino
authors.forename: Pasqualina
authors.initials: P
authors.lastname: Naddeo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Desiderio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pirozzi
authors.forename: Alfredo
authors.initials: A
authors.lastname: De Rosa
authors.forename: Luigi
authors.initials: L
authors.lastname: Laino
authors.forename: Lucia
authors.initials: L
authors.lastname: Altucci
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Papaccio
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D056284:Histone Deacetylase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D056464:Histone Deacetylase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis* / Q000235:genetics; D053495:Osteopontin / Q000378:metabolism; D014162:Transfection; D014635:Valproic Acid / Q000494:pharmacology*
chemical_list: D056572:Histone Deacetylase Inhibitors; D015675:Osteocalcin; D053495:Osteopontin; D014635:Valproic Acid; C110550:HDAC1 protein, human; C533423:HDAC2 protein, human; D056284:Histone Deacetylase 1; D056464:Histone Deacetylase 2
keywords: DPSC; HDAC; Osteogenesis; Valproic acid